1. Field of the Invention
The present invention relates to the technology of acquiring an image, and more specifically to the technology of acquiring a high-resolution image.
2. Description of the Related Art
For example, when a sample image observed by a microscope is captured, capturing a high-resolution image can be desired depending on the type of a sample to be captured. On the other hand, in an image acquisition apparatus for recording an optically captured image as digital data such as an electronic camera etc., the resolution of an image is determined by the number of pixels of the image pickup device used for the image acquisition apparatus. However, an image acquisition apparatus provided with a high-resolution image pickup device is generally expensive.
The technology of capturing a high-resolution image without increasing the number of pixels of an image pickup device is disclosed by, for example, the Japanese Laid-open Patent Publication No. 6-225317 and the Japanese Laid-open Patent Publication No. 2003-283887. In the technology, a high-resolution image is acquired using a plurality of images captured by shifting pixels. The technology is to perform image processing on an image captured without shifting pixels using a plurality of images captured by shifting the spatial relative position between an optical image formed on an image pickup device and the image pickup device by a pitch of one or less pixel, and acquires an image of the resolution of the number of pixels higher than the image pickup device. However, since a pixel shifting operation and an image acquiring operation are repeated in the technology, an appropriate image may not be acquired for a subject whose aspect changes with the lapse of time. For example, when a subject is a fluorescent observation sample, a long exposure time is required to acquire an image of pumping light of a smaller quantity of light, and fading gradually grows with the lapse of time after the pumping. Therefore, when an image of a fluorescent observation sample is acquired in the pixel shifting method, unevenness may occur on the acquired image.